• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.40 no.12
• /
• pp.801-807
• /
• 2016

This paper aims to compare and study the cooling performance of a battery system in accordance with the inlet and outlet geometry of the air passage in an EV. The arrangement and the heat source of the battery module were fixed, and the inlet/outlet area and its geometry were varied with the analysis of the cooling performance. The results of this study provide suggestions for the air flow stream line inside of a battery, the velocity field, and the temperature distributions. It was confirmed that the volume flow rate of air should be over $400m^3/h$, in order to satisfy conditions under $50^{\circ}C$, which is the limit condition for stable operation. It was also revealed that the diffuser outlet geometry can improve the cooling performance of battery system.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.5 no.2
• /
• pp.1-7
• /
• 2001

To protect combustion chamber from high temperature combustion gas, regenerative cooling is used for most liquid rocket engine. Although regenerative cooling is the most effective way to protect the chamber from high heat flux, realization of this system requires detail analysis, manufacturing technique and high cost. To demonstrate the possibility of applying regenerative cooling to a real rocket engine, the hot fire test has been carried out for the sub-scale liquid rocket with the water cooling system. The main purpose of the test is to identify the problem area of design, safety and cost effective manufacturing technique. The coolant passage was 3 mm in width and wall thickness was 1 mm with stainless steel. Maximum combustion time and pressure were 60 seconds and 400 psi, respectively. The flow rate of coolant was reduced gradually from 2 kg/s to 0.12 kg/s throughout firing test, combustion chamber was visually examined and no dwfect was observed.

• Asian-Australasian Journal of Animal Sciences
• /
• v.24 no.9
• /
• pp.1199-1203
• /
• 2011

The objective of this study was to examine the binding potential of sperm to the epithelium of the sperm storage tubules (SST) in vitro and in vivo to assess the functional maturation of fowl sperm. Sperm from the testis, epididymis, as well as the proximal, middle and distal vas deferens were incubated in vitro with either the uterovaginal junction (UVJ)- or infundibular tissue containing SST at $39^{\circ}C$ for 30 min. Aliquots of sperm were also artificially inseminated into the uteri of hens, and the UVJ and infundibulum were collected 24 h post artificial insemination (AI). After incubation and AI, tissues were washed to remove loosely adhered sperm and subjected to fluorescence staining with 4', 6-diamidino-2-phenylindole, dihydrochloride (DAPI) for counting the number of bound sperm per 0.25 mm2 of surface area. Sperm from the testis, epididymis, and the three segments of the vas deferens exhibited their differential (p<0.05) binding capacity, which increased gradually from the testicular to distal vas deferens sperm under both in vitro and in vivo conditions. Existing similar trend, sperm, regardless of their source had a lesser affinity to bind to the epithelium of the infundibular SST than to the UVJ-SST. These experimental results suggested that fowl sperm may undergo gradual changes in the process of functional maturation, whereby they gain the ability to bind to the epithelium of the SST during their passage through the male reproductive tract (MRT).

• Journal of Korea Multimedia Society
• /
• v.15 no.4
• /
• pp.472-484
• /
• 2012

Raised or plain block is widely used for the pedestrian's safe passage. The insincere construction, insufficient maintenance and obstacle overlaid on the pavement cause pedestrian's accidents. This paper proposes a method to detect brick path by analyzing the shape pattern and texture feature of brick located in visible distance for a safe passage. A brick appears to a regular type because of its specific shape which repeats with its sized gap and its type varies according to the surrounding environment or use. This paper shows a method which extracts the shape pattern by analyzing single surface polygon and its frequency appearing in road area. The shape pattern is used to detect similar shape regions. Some regions are not detected because extraneous substances or chopped bricks distort the original shape. This problem can be solved by analyzing the texture feature vector. The analyzed vector of the previously detected regions yields the Gaussian distribution. This value in each undetected region is computed and checked whether it's satisfied with Gaussian distribution or not. The satisfied region is detected as the brick path. The experiment was performed with the various type's bricks to recognize so that the results showed as accurate as 95.9% in average.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.48 no.9
• /
• pp.717-724
• /
• 2020

We study the closing characteristics of a self-sustainable poppet valve which serves as a main oxidizer shut-off valve for liquid rocket engines. Numerical analysis for predicting closing transient responses are presented and the calculated results have been verified by a comparison with experimental data. The effective area of a pilot gas discharge system and the pressure distribution of passage flow around the valve moving part are shown to be main parameters in determining the closing characteristics for dry and cryogenic conditions, respectively. Moreover, it is presented that the passage flow pressure at the valve closing moment as well as the valve closing velocity can be effectively adjusted by the appropriate employment of the pilot gas.

• Geomechanics and Engineering
• /
• v.14 no.5
• /
• pp.407-419
• /
• 2018

In order to investigate flow characteristics after water inrush from the working face in process of karst tunnel construction, numerical calculation for two class case studies of water inrush is carried out by using the FLUENT software on the background of Qiyueshan tunnel. For each class water inrush from the tunnel face, five cases under different water-inrush velocity are simulated and researched. Three probing lines are selected respectively in the left tunnel, cross passage, right tunnel and in the height direction of the tunnel centerline. The variation characteristics of velocity and pressure on each probing line under the five water-inrush velocities are analyzed. As for the selected four groups probing lines in the tunnels, the change rules of velocity and pressure on each group probing lines under the same water-inrush velocity are discussed. Finally, the water flow characteristics after inrush from the tunnel face are summarized by comparing the case studies. The results indicate that: (1) The velocity and pressure change greatly at the intersection area of the cross passage and the tunnels. (2) The velocity nearby the tunnel side wall is the minimum, while it is the maximum in the middle position. (3) The pressure value of every cross section in the tunnels is basically fixed. (4) As water-inrush velocity increases, the flow velocity and pressure in the tunnels also increase. The former is approximately proportional to their respective water-inrush velocity, while the latter is not. The research results provide a theoretical basis for making scientific and rational escape routes.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.8 no.5
• /
• pp.1192-1200
• /
• 2007

A general rainfall outflow in urban drainage has early time of concentration because urban drainage areas are most paved area. In general, rainfall outflow is flowed in drainage pump station and is discharged to rivers in urban areas. However it is excluded through drainage pumps about a heavy rainfall which exceed the design rainfall and the rainfall outflows increase the urban inundation risk. A current pump operation is control according to water level of collecting well or reservoir in drain pump station. But recently, the localized downpours are happened frequently in urban drainage and the current pump stations are frequently incapable of the heavy rainfall outflows. In this study, a real urban inundation was simulated and the drain capacity of drain pump station was evaluated by analysis about flood-factor in urban underground passage. Then the analysis about the inundation was done by the simulation about the real rainfall which cause the inundation. Also, in the simulation the inundation risk and the evaluation of flood-factor were analyzed according to change of the pump operation rule.

• Journal of Korea Water Resources Association
• /
• v.52 no.spc2
• /
• pp.855-863
• /
• 2019

The efficiency of fishway installed in rivers can be directly evaluated by means of fish monitoring. On the other hand, when it is difficult to monitor the fish in certain conditions, or when planning a fishway, the efficiency can be evaluated indirectly through the hydraulic analysis. In this study, the hydraulic analysis technique for evaluating the efficiency of a fishway was presented. The River-2D model with the fish physical habitat module was used for the analysis of the attraction efficiency, and the weighted usable area was proposed as an index of the efficiency. In the analysis of passage efficiency, the three-dimensional model, Flow-3D, was used as an evaluation tool to describe the fluid behavior on a hydraulic structure with free surface. The ice-harbor type fishway at Baekgok weir in the Deokcheon River was selected as a test-site, and the efficiency was estimated using the hydraulic analysis. And then it was compared with fish monitoring data acquired from the river. As a result, it is difficult to replace the hydraulic analysis results with the efficiency quantitatively, but it can help to grasp the general tendency.

• Journal of Korean Port Research
• /
• v.13 no.1
• /
• pp.133-146
• /
• 1999

Mokpo coastal area is connected to the adjacent a long river and two large basins. It is essential for port planning coastal zone management and environmental impact study to analyze the data related to the ship operation and variation of current and water quality due to the development of water area including dredging reclamation and estuary barrage. The Yongsan river estuary weir and Yongam-Kumho basins discharge much of water through water gates for the purpose of flood control and prohibit salt intrusion at the inland fresh water area. To meet this purpose discharge through the gates have been done at the period of maximum water level difference between inner river and sea level. This discharged water may cause the changes of current pattern and other environmental influences in the vicinity and inner area of semi-closed Mokpo harbor. In this study ADI method is applied to the governing equation for the analysis of the changes on current pattern due to discharged water. As the results of this study it is known that the discharging operation causes many changes including the increase of current velocity at the front water area at piers approaching passage and anchorages. Discussion made on the point of problems such as restricted maneuverability and the safety of morred vessels at pier and anchorage. To minimize this influence the linked gate operation discharging warning system and laternative mooring system are recommended.

• Journal of Korea Game Society
• /
• v.17 no.5
• /
• pp.113-122
• /
• 2017

The location of the objects that make up a game can be an element of immersion for players. repeatedly appearing at the same position, the fun may be reduced, and as the play time elapses, the players will feel the game's fun as they appear in a larger area than at the beginning of the game play. This paper is a study to find out the location of objects according to the passage of time and to see how players controlled these objects. First, foreground images are extracted and accumulated using OpenCV programming language. The accumulated result is displayed as a heat map image. Second, the mouse movement area is detected using the mouse tracking program and compared with the heat map image, so that the screen area in which the player is interested can be known.